Conventionally, there has been known a three-plate type projector including a color-separating optical system that separates a light beam irradiated by a light source into three color lights, three optical modulators that modulate the respective color lights in accordance with image information, and a color-combining optical device that combines the light beam modulated by the respective optical modulators.
In order to downsize the projector, an optical device in which three optical modulators are bonded and fixed relative to a color-combining optical device is applied to such a three-plate type projector (for example, see JP2000-221588A).
In this optical device, the three optical modulators are bonded and fixed relative to the color-combining optical device with a plurality of pin spacers being interposed.
To be more specific, each of the optical modulators includes an optical modulation element for modulating a light, and a holder frame having an opening corresponding to an image formation area of the optical modulation element and housing the optical modulation element. Here, four holes are formed on a periphery of the opening of the holder frame. While housing and holding the optical modulation element in the holder frame, by respectively inserting four pin spacers to the four holes formed on the holder frame, end surfaces of the respective pin spacers are bonded and fixed on a light-incident surface of the color-combining optical device, and also outer surfaces of the respective pin spacers are bonded and fixed on inner surfaces of the respective holes, so that the three optical modulators are bonded and fixed relative to the color-combining optical device.